Glucomannan has many health benefits, but it is best known as a weight loss aid. It is an important component of certain foods in Asian cuisine, such as shirataki noodles. I even have a few recipes on-site using these fiber-rich, low-carb noodles.
In this post, we’ll dive deeper into what glucomannan is and whether it’s really worth having in your pantry.
What Is Glucomannan?
Glucomannan is a type of soluble fiber. It’s found in konjac (elephant yam), the cell walls of yeast and bacteria, and in a few other plant species. The glucomannan that we eat in our diet mostly comes from the konjac root.
While not commonly grown in this part of the world, it’s catching on as an alternative to carb-heavy pasta (which may lack any substantive nutrition).
How Does It Work?
The health benefits of glucomannan come from its expansive properties. As a soluble fiber, it can absorb a lot of water and solidify it into a gel. This means that it can expand to fill up space in our stomach and increase our feeling of fullness… which may translate into weight loss!
Health Benefits of Glucomannan
Glucomannan may help with weight loss by:
- Reducing ghrelin (hunger hormone)
- Reducing insulin and leptin resistance (in type II diabetics)
- Normalizing blood sugar
- Slowing down the movement of foods through the gut
- Increasing beneficial bacteria in the gut
- Reducing inflammation
A review of 14 clinical studies in the American Journal of Clinical Nutrition found that glucomannan had an effect on weight loss. However, glucomannan’s effect on weight reduction is rather mild, at about 1% of the subject’s body weight.
It’s possible this is because glucomannan on its own may not be a very effective way to lose weight. However, when combined with dietary and lifestyle changes, it can be very effective.
When used together with dietary changes, glucomannan was quite helpful with weight loss. In a study involving 160 overweight subjects, glucomannan use helped increase weight loss by about 50 – 80% more than the placebo.
However, the authors state that the use of dietary fibers for weight loss is typically strongest initially. Then it decreases over about 6 months.
But Before You Stock Up on Shirataki Noodles…
My approach to weight loss goes way beyond supplements. It is far easier and healthier to deal with the root causes of excess weight. These causes may include inflammation, blood sugar, and hormone imbalances. Just by giving up inflammatory foods and adjusting carbohydrate intake, many of my clients have been able to lose weight.
Glucomannan may help with weight loss. But the best approach is to use it in combination with other diet and lifestyle changes. This will help produce long-lasting results.
The real benefits of glucomannan are in the ways it supports other aspects of health.
Reduces Cholesterol and Normalize Blood Sugar
As a dietary fiber, glucomannan can bind to bile acids in the gut and carry them out of the body in feces. This requires that the body use up more cholesterol to produce bile acids. This can help reduce blood cholesterol and blood fats.
Glucomannan also slows down the rate at which foods move from the stomach into the intestine. This increases satiety and slows down carbohydrate absorption. It can help normalize blood sugar and may help with type II diabetes.
Clinical studies show that glucomannan can significantly reduce total cholesterol, LDL (bad) cholesterol, triglycerides, and fasting blood glucose.
Feeds Beneficial Gut Bacteria
There is no question that our gut bacteria are very important for health. Glucomannan resists digestion by our digestive enzymes. But our gut bacteria can ferment the soluble fiber into short-chain fatty acids. This process is referred to as Saccharolytic Fermentation. Unlike other types of fiber (like inulin) glucomannan does not cause as much gas.
There are many health benefits to feeding good gut bacteria. Commensal and keystone species such as Bifidobacteria and Lactobacilli feed well on short-chain fatty acids glucomannan makes. Examples of short-chain fatty acids include butyrate, propionate, and acetate.
Modulates Immune Function
In rats, the use of dietary fibers has a balancing effect on the gut immune system. This can help reduce inflammation. Serum IgE levels (antibodies) are significantly lower in rats fed glucomannan than other types of dietary fiber. It might be particularly helpful for those with allergies, eczema, and asthma.
Feeding eczema-prone mice with glucomannan helps reduce inflammation and prevent eczema breakouts.
Promotes Digestive Health
Glucomannan is great for gut bacteria, but it is also a soluble fiber that can absorb a lot of water for its volume. It can bulk up stool and speed up the transit time in the large bowel. This helps reduce constipation.
As a fermentable fiber, it seems to produce less gas than other types of fiber supplements. It is also less likely to produce bloating or other side effects.
Reduces Colon Cancer Risk?
In rats that are fed a high-fat, no-fiber diet, using konjac fiber helps reduce risk factors for colon cancers. It increases beneficial bacteria, short-chain fatty acid levels, and natural anti-oxidants in the gut.
Those with an unhealthy diet may have success using glucomannan for additional protective benefits.
Removes Toxins and Mycotoxins From the Gut
Pigs fed with moldy grains suffer from brain and immunological problems due to the mycotoxins in the grain. Feeding these pigs glucomannan can reduce mycotoxin levels. This reduces its negative effects. Glucomannan may offer relief to people suffering from toxic mold in buildings with water damage.
The metabolism of the thyroid hormone in the gut controls thyroid hormone levels. In hyperthyroid patients, using glucomannan (with medications) more effectively reduces thyroid hormone levels to healthy levels than medications alone.
However, there is no evidence of whether glucomannan can reduce thyroid hormone levels in healthy or hypothyroid subjects. The authors of this study suggest that glucomannan works like cholestyramine, which is also a drug that can remove mycotoxins from the gut.
Check out this podcast episode to learn how to get a correct thyroid diagnosis.
How to Take It
In many scientific studies, 1 gram taken 3 times a day seems to be a general starting dose.
You may consume glucomannan as shirataki noodles (I get them discounted from Thrive Market), shirataki blocks, or as a food product.
Potential Dangers to Consider
Glucomannan absorbs a lot of water and expands. So it is safer to consume glucomannan after it dissolves and expands in water. For this reason, taking glucomannan as a powder or a food product is a better choice than capsules.
There have been some reports of esophageal obstruction from swallowing glucomannan without enough water. Obstruction of the gut may also be a concern. You should always drink a lot of water if you take glucomannan supplements.
Some people may also experience bloating and indigestion. This is especially true if you suffer from small intestine bacterial overgrowth. Exercise caution if you don’t typically ingest large doses of soluble fiber. If you are prone to digestive issues, it is a good idea to start at a low dose and slowly increase it over time.
Glucomannan may interfere with the absorption of certain nutrients or medications. Therefore, it is a good idea to take other nutritional supplements and medications away from glucomannan. As always, speak with a health care professional before you begin taking supplements.
Other Uses for Konjac Root
Have you ever heard of a konjac sponge? (And no, you don’t eat it!) Check out this post for one of my favorite tools in my natural skincare routine.
This article was medically reviewed by Dr. Tim Jackson. He is a Doctor of Physical Therapy and Orthopedic Rehabilitation, and a Functional Medicine provider. He holds a B.S. Degree in Health Science and Chemistry from Wake Forest University. As always, this is not personal medical advice and we recommend that you talk with your doctor.
Have you tried glucomannan or shirataki noodles? Let us know your experience in the comments!